Nitrous oxide (N2O) injection systems and chargers for vehicles are designed to temporarily boost the power output of internal combustion engines. Such systems inject vaporized nitrous oxide into the combustion chamber of an engine during the intake stroke of the piston to provide more oxygen for combustion than would otherwise be available during normal operation. The additional oxygen in the combustion chamber allows extra fuel to also be injected into the combustion chamber. The combined increase in fuel and oxygen results in a more energetic combustion stroke, with greater power being transferred back to the piston and drive shaft with an ultimate increase in the horsepower output of the engine.
For effective operation of a nitrous oxide injection system, a balanced air/fuel (or oxidizer/fuel) mixture flowing into the engine must be properly maintained throughout the boost phase. This can be difficult, because a precise increase in fuel must be provided to balance the additional oxidizer (in the form of vaporized nitrous oxide), which in turn can be difficult to measure and control. A common problem with nitrous oxide injection systems is that the nitrous oxide is often stored as a compressed liquid inside a pressurized bottle, which pressure can decrease with use and provide proportionately less nitrous oxide per release valve setting. Compounding the issue is the cooling effect that the evaporating nitrous oxide liquid has on the intake air as it is released into the engine's intake system, which reduces the intake air's temperature and increasing its density. While this can provide even more oxidizer (i.e. oxygen) to the engine and enhance the power charging aspects of the nitrous oxide system, it can also upset the delicate balance of oxygen and fuel and can lead to an excessively lean mixture flowing into the combustion chamber.